An unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts has been studied as an altative route for the production of propylene.Complete conversion of 2-pentene and propylene yield as high as 88 wt％ were obtained under mild reaction conditions at 35 ℃ and atmospheric pressure.Unlike the conventional metathesis of ethylene and 2-butenes in which isomerization is a competing side reaction,the isomerization of 1-butene product from the unconventional metathesis of ethylene and 2-pentene to 2-hutenes can further react with excess ethylene in the feed,resulting in additional increase in propylene yield.The secondary metathesis reaction was found to be favored under ethylene/2-pentene (E/2P) molar ratio ≥3 and gas hourly space velocity (GHSV) ≤ 1000 h-1 at the reaction temperature of 35 ℃.No catalyst deactivation was observed during the 455 min time-on-stream under the selected reaction conditions.